The Rules of Murder

Detective fiction is the new kid on the literary block. Unlike romance, which traces its roots back to the middle ages, the detective story burst on the scene in 1841 with Edgar Allen Poe and his brilliant detective Auguste Dupin.
Several decades later, Sherlock made his debut in  A Study in Scarlet and the game was really
afoot. By the twenties and thirties the so-called Golden Age of Detective Fiction arrived, with the likes of Agatha Christie and Dorothy Sayers plying their trade. As many of these writers were based in London, it was perhaps inevitable that they formed their own society--the Detection Club.

Like any club worth its salt, there was an elaborate initiation ceremony, including this sacred oath:
Do you promise that your detectives shall well and truly detect the crimes presented to them using those wits which it may please you to bestow upon them and not placing reliance on or making use of Divine Revelation, Feminine Intuition, Mumbo Jumbo, Jiggery-Pokery, Coincidence, or Act of God?
Members of The Detection Club, detecting the Sunday Times
Personally, I have no problem with most of the oath, though I enjoy a little jiggery-pokery now and again. In addition to the blood oath, members were also expected to follow ten commandments in writing a mystery. The rules were set down in stone by Ronald Knox in 1928. Let's check out a few of these rules to see how well they've stood the test of time.

The criminal must be named in the early part of the story, but must not be anyone whose thoughts the reader has been allowed to follow I have no problem with the first part as it's just a question of playing fair with the reader. Also, the interplay between the sleuth and killer is a big part of the fun in any murder mystery. However, I'm not so sure about about that last bit. If Agatha Christie had taken this rule to heart, she'd have never written the classic The Murder of Roger Ackroyd, where--spoiler alert--the killer narrates the tale. It's one of mystery's great novels and yet at the time of its publication, some contemporary reviewers were so upset, they  actually called The Grand Dame of Mystery a cheat.

Not more than one secret room or passage. I guess Dan Brown didn't get the memo.

No hitherto undiscovered poisons may be used, nor any appliance which will need a long scientific explanation at the end. A good rule as the real deal--or poison--is almost always preferable to some made-up concoction. I added "almost" because this was another rule Christie broke, most notably with the fictitious hypertensive drug Serenite in A Caribbean Mystery and equally fake sedative Calmo in The Mirror Crack'd from Side to Side

 The detective must not light on any clues which are not instantly produced for the inspection of the reader. In other words, play fair with your readers, or else you won't have them for very long! In the opening chapter of Death at China Rose, I slipped in a little fact that virtually identifies the killer. Of course neither my sleuth nor the reader has the context to use that information at that early date--sneaky, but fair.

Twin brothers, and doubles generally, must not appear unless we have been duly prepared for them. I've always found the twin thing boring and done to death, though an episode of Endeavour which involved  twins kept my interest. But then I'm nuts about Shaun Evans so anything his Morse does is fine by me! However, if a writer wants to go with twins, I'd advise caution. Extreme caution.

So, are the rules still viable? Before I get to my final verdict, here's  a quick cautionary tale.

When I attended the University of Florida, postmodernism was the big thing. In one of my classes the professor instructed us to write an paper without any rules.

Elvis Presley 
rocking his moneymaker in jail
I took him at his word and constructed a frenetic paper that incorporated everything from Derrida to Moby Dick to Elvis's phallus. (Trust me, you don't want to know.)

Writing the paper was a liberating experience. I jumped from topic to topic in a steam of consciousness that would have done Joyce proud. It was fun and I even got an A!

A year of so after the fact, I was going through some old papers and came across my forgotten masterpiece. A sappy smile on my face, I started reading. Pretty soon, my smile twisted into a grimace. The damn essay made no sense. It was just a bunch of random thoughts tied together with string and spit, signifying nothing. (Sorry, Elvis.) The fact is that rules exist for a reason. If you're going to break them, you too need a reason--a good one

My rule is that rules are useful, unless they're not!

Agatha Christie Memorial in London's West End